SMILES-based methods [1]} are infeasible for scaffold-based tasksA drug design scheme where the drug candidates are designed from the given scaffold. since molecular structures can substantially change through the sequential extension of the SMILES strings. Also, as explained in the Introduction, atom-based generation methods such as You et al.'s GCPN [2]} inherently suffer from unrealistic generated molecules. Thus, we focus our discussion on motif-based generation methods.
